According to the octet rule noble gases should not form compounds but xenon and krypton form compounds like $\ce{XeF2}$, $\ce{XeF4}$, $\ce{XeOF2}$ and $\ce{KrF2}$ respectively. Why?
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2$\begingroup$ This question and its answers should apply to your question. It's a slightly different context but the idea is the same: the octet rule is rather useless beyond Period 2. $\endgroup$– orthocresolOct 17, 2015 at 15:04
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1$\begingroup$ Basically, the octet rule only applies to a very specific subset of possible compounds. In general, there is no octet rule. $\endgroup$– bonOct 17, 2015 at 15:06
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2$\begingroup$ Nobody told Xe or Kr that they had to follow the octet rule (which is more of a rough guide than a rule). Chemistry has many 'rules' that only apply in limited circumstances. Don't blindly apply rules. $\endgroup$– Jon CusterOct 17, 2015 at 15:50
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$\begingroup$ See my answer to the question ortho linked to learn more about the octet rule. Also, all compounds (e.g. $\ce{XeF2, KrF2}$) with noble gases are conforming with the octet rule if applied correctly. $\endgroup$– JanOct 17, 2015 at 18:05
1 Answer
When we say that noble gases are stable it means that they are more stable than the rest. Yet it is to be considered that even these have ionisation potential ;though high. if we make a noble gases react with such ions that help in their bonding then we can have a compound of noble gas. Search this on Google.
The first published report, in June 1962, of a noble gas compound was by Neil Bartlett, who noticed that the highly oxidising compound platinum hexafluoride ionised O2 to O+ 2. As the ionisation energy of O2 to O+ 2 (1165 kJ mol−1) is nearly equal to the ionisation energy of Xe to Xe+ (1170 kJ mol−1), he tried the reaction of Xe with PtF6. This yielded a crystalline product, xenon hexafluoroplatinate, whose formula was proposed to be Xe+ [PtF 6]− . It was later shown that the compound is actually more complex, containing both XeFPtF5 and XeFPt2F11. - Wikipedia, noble gas compounds
This was the first real compound of any noble gas.